1. Field of the Invention
The present invention relates to hydraulic couplings used in undersea drilling and production applications and seals used in those couplings. More particularly, the invention involves an undersea hydraulic coupling with a tapered probe that will displace sea water from the cavity between the coupling members before radial seals engage the circumference of the probe.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with soft seals positioned within the female member to seal the junction between the male and female members. The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion, or probe, at one end having a diameter approximately equal to the diameter of the large bore of the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, or O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its outer circumference. The hydraulic fluid is then free to flow through the female and male members of the coupling, and seals prevent that flow from escaping about the joint and the coupling.
In some instances, a check or poppet valve may be installed in the female member and also in the male member. Each valve opens when the coupling is made up and closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith, III, assigned to National Coupling Co., Inc. of Stafford, Tex., an undersea hydraulic coupling and metal seal is disclosed. This patent provides an undersea hydraulic coupling with a reusable metal seal which engages the circumference of the probe when it is positioned within the female member bore. The metal seal is held in place by a retainer. When the male and female members of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
When the male member of an undersea hydraulic coupling of the foregoing type is connected to the female member, while the couplings are subsea, sea water may be trapped in the bore and enter the hydraulic lines attached to the coupling members. During disconnection of the coupling members, when the male member is withdrawn from the female member bore, a low pressure area or vacuum may be created in the bore. This vacuum may urge the seal into the bore, and may increase the difficulty of disengaging the male from the female coupling member. A coupling design addressing these problems by including a passage for venting sea water into or out from the cavity while the male member is disengaging or engaging the female member is disclosed in U.S. Pat. No. 4,813,454 to Robert E. Smith III assigned to National Coupling Company, Inc. of Stafford, Tex.. The patent discloses an undersea hydraulic coupling with pressure balancing ports between the central bore of the female member and the outer surface of the body.
An improved undersea hydraulic coupling is needed having one or more seals around the circumference of the male member, and which displaces sea water that is trapped between the male and female members while the coupling is being assembled and before the seals engage the male member or probe.